shutter-shudder
An involuntary muscle-twitching dat a camera-shy person feels from either having to press da release-button to take a photo, or when he hears da click of da camera when a picture is being taken of him.
One simple way to mostly eliminate image-blurring from fairly-minor shutter-shudder is to use a fast exposure-speed (and a flashbulb, too, if it's fairly low-light conditions); you may need to use a suitably large lens and wide aperture-setting to accommodate said swift-click camera-snap.